Question

ПОМОГИТЕ СРОЧНО с алгеброй !!
Найди значение выражения:

Answer 1

$\displaystyle\bf\\-5Cos(3\pi+x)-2Sin\Big( \frac{3\pi }{2}+x\Big) =-5Cos\Big[2\pi +(\pi +x)\Big]+2Cosx=\\\\\\=-5Cos(\pi +x)+2Cosx=-5\cdot(-Cosx)+2Cosx=\\\\\\=5Cosx+2Cosx=7Cosx\\\\\\Cosx=-\frac{1}{7} \\\\\\7Cosx=7\cdot\Big(-\frac{1}{7} \Big)=-1\\\\\\Otvet \ : \ -1$